Treated casein and process



Patented Jan. 27, 1942 UNITED: STATES PATENT m Izsusss p I i N. Y.,asaignori to The Borden Company, New York, N. Y., a corporation of lewJersey Application January 3, 1940,

. Serial so. 313,302

iclaims. (Cl. 1065-146) v -fore in common use have been entirelysatlslac It is well known that caseln'dissolves in alkaline solutions,suchas solutions of borax, tri-- sodium phosphate, soda ash, potassiumcarbonate,

ammonia, triethanolamine, as well as in the presence of nm. The amountsof these solvents necessary to dissolve a particular casein and the 7properties of the casein solution when made will depend (among otherfactors) upon the quality of the particular casein used and this in turndepends upon the manner in which the asein has been prepared from themilk. It is tions to foam. Such foamy casein solutions are particularlytroublesome in most manufacturing -p w A for instance, when caseinismixed with.

graphing in particular. In so coating paper, it is customary to make upwhat is-termed paper coating color," namely water containing dissolvedmilk casein and suspended pigments such as clay, satin white, blancuflxeand-others (white and/or colored), sometimes also containing dissolveddyestuifsotanalkaliresistlngnature. when the color has a tendency tofoam during the.

coating operation, bubbles may be formed on the surface of the paper,which break during the drying-of the coating, causing pin holes and, a

in the usual way, does not to the same extent other imperfections in thecoating. Such-coated paper does not give a clear and satisfactorysurface design, when printed or lithographed.

Many proposals have been made heretofore for 'ameans of preventing thefoaming tendency of casein. including the prevention of foaming of papercoating color containing casein. Also to prevent this tendency in caseinsolutions and mixtures of casein with other substances in general, andso far as we are aware of with only varying degrees of success, smallamounts of lard oilmixedwith sulphonatedoilshave beenrecommended toassist in preventing or limiting thisfoaming tendency. Other suggestionshavc'been made including the'additionof amyl alcoholorpine oil to thecasein solution or to. paper coloror sizing material. Sometimes it hasbeen found necessary to also add small amounts of foam abet-ins agentsafter a papercolor mix .put into the color box or foimtain' ofqthe'paperwell known that diilerent commercial ca'seins vary a 4 great deal inregard to the tendency of the solucoating'm'ixtur'ea, a small amount'oftributyl cit- .tributylcitrateJ! added to). paper coating color 'tory. e

In our search fora toan'i abatenwe have dis-' covered that there arecertain chemicals ,which 5 may befof value as foam abaters or arrestershen added to the liquid coating mixture (the color") and yet whichsubstances applied as a coating to the driedparticles of casein prior todissolving same,-do not act in the same manner as regards preventingfoam; We have foundthat certain chemicals are relatively inemcient asfoam abaters when added to the prepared coating mix.- ture or to thecasein solution, whereas, small amounts of the samechemicals when'coatedonto and thepasein thereafter dissolved by the methods and tested forfoam development..: produce remarkably .sood results,

either from the standpoint .of' largely arresting the tendency to 10amin a simple solution of the casein, .or in the finalmineral-casein-water mixture referred to as color.

. We have in our research inadeycareful with apgreat varietyof-substances in order to determine their value as :f oam arrestersorfoam abaterswith casein solutions, by means *0! coat ing or sprayingonto the dry casein, small amounts of various substances for thispurpose. During this series of. tests we have found for example thatwhen a. relatively small percentage of tributyl phosphate is mixed into.a casein solution for-into a paper fcolorf it is fairly satisfactory fortendency to foam, yetthis same tributyl phosphategwhen putonto the drycasein (e. g. as a spray), and the casein thereafterdissolved stop orarrest-the foaming tendency. In a number of'otherinstances'this peculiarcondition has been found wlthvvarious. chemicals; and with certain other'chemicals, the reverse condition the te c of pa r-comps m urescontaining toioam, by applying, to the soliddry case which st? be'disclved and used in new rate. shquad be applied to the solid 7 m". ispreferably in the air-' WP?! WWW "4 w n is dwlvgd in' alkalt In factwhenan-equal. amount of the.

reduce the;t endency:.to.foam to such an extent" coating machine..Noneolr'the methods hereto-"j' as when applied to the solid casein,before dissolving. Thus, very useful results have been produced byspraying the tributyl citrate upon the dry casein (or in any othermanner coating the casein particles with the small amount of tributylcitrate). and subsequently dissolving the casein in an alkali solution,and incorporating the pigments, etc. The best amount of the tributylcitratetobeusedwithaparticularcaseimto give the most satisfactoryresults, should iflrst be determined as for that particular lot ofcasein. In using high grade caseins, we have sometimes found smallamounts such as 0.2% to be satis factory, although in some cases wherethe foaming tendency of the casein is high, we prefer to use much largeramounts such as 1%. Based on our experimentation to date, we believethat not more than 5% of the tributyl citrate would be necessary in anycase. After adding the citrate, the casein can be dissolved at once, orafter stora e. shipp etc- In order to more fully explain our inventionwe give herewith by way of illustration, several examples of theutilization of the discoveries leading up to this process, although wedo not limit ourselves in any way to the examples cited.

Exams: 1

Into a suitable mixer such as the usual spiral measurement taken toindicate the degree of speed with which the developed foam receded orbroke down. Thereaftehthe solution was allow the foam which wasdeveloped during this test to entirely recede.

ample N0. 1.

mixer containing the proper spiral agitator, we

placed 400 parts of ordinary commercial casein which had been ground,for example, to all pass through a standard 24 mesh wire screen. Thespiral in the mixer, by any convenient means, was made to revolve at afairLv rapid speed and thereafter we sprayed 1 part .25%) of com-.

mercial tributyl citrate onto the casein while being agitated in thespiral mixer. Thereafter, operation of the mixer was continued for aboutminutes, the material then removed from the mixer and tested for foamingtendency as follows:

100 gms. of the tributyl citrate treated casein was added. to 500 gms.of cold water, mixed to wet the particles and allowed to stand for aboutto' minutes. Thereafter we added I gms.

- of commercial 26 ammonia, the liquid mass,-

mixed thoroughly and thereafter the receptacle holding the mixture wasplaced in a water bath and heated, while stirring slowly, to about 140F. When the casein was completely dissolved we slowly added a further500 gms. of cold water to this solution, stirring it thoroughly toobtain a uniform solution which was then cooled to '15 Exams: 2

400 parts of casein, 3 parts of tributyl citrate, mixed and preparedexactly as described in Ex- The casein was from the same lot as used inExample 1; A 100 gram sample of this mixture was then dissolved andtested for foaming tendency in the exact manner described under ExampleNo. 1.

' The results of these tests are recorded under Table I. v

Other tests with other types of casein known to much greater foamingtendencies than th casein used in Examples 1 and 2, were also treatedwith various amounts of tributyl citrate by means of spraying or oiling"the ground dry casein. one particular casein being one known to beextremely difficult to use in commercial operations, from the standpointof dissolving or preparing the solution because of its great tendency tofoam (even foaming over the mixing kettles while the solution is beingprepared, unless extra care is used in its preparation). Such'acaseinwasusedinExamples3 and4.

F. We then made a test to determine the relative foaming tendency ofthis treated casein by the following method:

Into a one-quart capacity cylindrical glass jar there was placeds400cc.. of thecasein solution above referred to and the height of theliquid was marked on the Jar. One egg-beater mounted on a SunbeamMix-Master mixer was placed in the solution. The beater was started, thebeater running840R.P.M.andthebeatingwasoontinued' for exactly 6 minutes(bya stop-watch). Then the beating was discontinued and the height ofthe liquid plus the foam developed was quickly measured. This bysubtraction showed the "height of foam" developed fromthe top oftheoriginalliqmdintheiartothetopofthe foam layer. This height of foamdeveloped applies to the particular casein used in this example,modified by the tributyl citrate.

After having measured the height of foam, the solution in the jar wasallowed to rest undisturbed for another 5 minute period and a secondExmm: 3

400 partsof a casein (known to be excessively foamy), 3 parts oftributyl citrate. Procedure for preparation was exactly the same asdescribed under Example 1. Thereafter a sample of grams of this mixturewas dissolved and the "height foam determined as described underExample 1. The results ofthese tests appear in Table I.

Exmu 4 dissolved and tested for height of foam" as de-l scribed underExample- 1. The results of these tests appear in Table L a control(without thecitrate ma) air-me casein usedinltxamples Sand 4, wastreated andtestedinthesamewsy.

I m5 400 parts of commercial sodium cascinato groundtoaiinenesssothatallwillpassthrough *aMmeshscreen. Tothiswasadded4partsof tributylcitrate following the method as described in Example 1'. Thereafter, 100grams of thetreatedsodhimcaseinatewas addedtomcc.ofooldwater,mixedtowettheparticlesand immediately heated (becausesodium caseinate is soluble in water without the additiomof othersolvents) to about 140. 1''. After the casein was dissolvedx we added#0. cc. of cold water and stirredthemixture-mtilitwasinauniform outtributyl citrate was similarly amuse consistency. Thereafter thissolution was tested for its "height of foam, as per the method describedunder Example 1 and the results are recorded in Table I.

A sample of this same control, and the results are shdwn in Table I.

other tests were made by preparing a com-5 plete color mixture andthereafter a foamtestwiththiscolormixturebytheusual well-establishedmethod (described below) to determine the "foam index in paper coatingcolor mixtures. Inoneoftheseteststhematerlalpra pared under Example 3was used (with pigments).

In another test the same casein without'treatment with trlbutyl citratewas employed. .The results of thesetests areindicated in Table II. a

The method used for preparing and making the paper color foam index testwas as follows:

A casein solution was made up at a concentration of 1 part of theparticular casein-to 5 parts caseinate withtreated. as a.

citrate. We do not wish to limit our invention to any definite amount of"trlbutyl citrate to be vaddedtothedrycaseinbutwehavethusfar" willbesumcient'in all cases..

found that not over 1% of tributyl citrate seems to besufilcientonanyofthe easeinswe-have examined. We believe that quantities below 5% All ofthe above specific disclosure, including the above examples and theabove tables. refers to the treatment of milk casein.

The invention is also applicable I tory results to the treatment of"vegetable casein, which may be, to some extent. considered as asubstitute for milk casein in the paper coating art. This material alsooften shows a;

troublesome foaming tendency. Various tests were made by treating theliterature and in commerce, as "vegetable casein or "soya casein), withtributyl citrate by the process described herein, in order to reduce thefoaming tendency of products of this nature, namely, isolated vegetableprotein. Tests were made as follows: An isolated soybean protein (whichin-many of its properties is similar;

to milk casein) was purchased on the market.

'1hisisofaty'pethatiscommerciallyofl'eredto I ,the trade regularly. so

Exams: 6 Into a suitable mixer such as the usual the proper spiralagitator, we placed of water, using ammonia as'given in Example 8 as thesolvent for the casein. Other solvents could be used as long asthesamesolventis.

used in comparative tests A clayslip-was madeup bymixing 1 part of with1 part of water to a smooth paste. To parts'of the clay slip were added06 parts of casein solution which is equivalent to 11 dry casein. Thiswas mixed until smooth 400 parts of dry ground soy-bean isolated protein(also sometimes called "soya casein). The spiral mixer,'by anyconvenient means, was made to revolve at a fairly rapid speed andthereafter we sprayed 1 part (0.25%) of commercial tributyl citrate ontothe isolated protein'while being agitatedin the spiral mixer. Thereafterthe mixing was continued for about 5 minutes, the material then removedfrom the mixer and tested for foaming tendencies. The procedurefordissolvingand testing the resulting mixture for foam ing tendency wasthe sameas that described under Example 1, with the exception that alittle andstrained throughawirescreentoinsure complete uniformity (a 100mesh screen was used.

in the present tests).

the clay-casein mix mixsothatthetopofitisefiinchbelowthe surface oftheliquid. At the end of two minutes stirring; the mix was allowed to standfor one minute. Immediately, thereafter, the weight of 100cc.ofthesotreatedmixtllrewa8determined. The loss in weight as comparedwith the weight of 100 cc. mentioned above,is termed the "foam index." 7

- Table 11 Foam index Color mix (casein not treated) 48.5

' 001m mix (casein; with tributyl citrate)Aswillbenotedfromtheresuitsindicatedin Table I and Table II, we obtain avery marked more ammonia was used as the solvent, namely 10 grams ofgramsasusedinExample 1.

Exam; 7

' The same procedure was followed as in Example 8 with the exceptionthat we used 2 parts (0.50%) of commercial trlbutyl citrate.

Exsssru 8 Same as Example 6, with the exception that we used 3 parts(0.75%) of commercial tributyl citrate. 1 j

' mixtur s .9

The same as Example 6, with the exception that we used 4 parts (1%) ofcommercial tributyl citrate. A v

The resulting solutions of the treated isolated soya protein (madein-Examples 6 to 9) were tested for foaming tendencies in the same man--i net as described under Example 1 and for pm?- pose of control, anuntreated sample of the same isolatedsoya protein (without the citrateadded) was dissolved in the same, manner as described decrease in thefoaming tendency in the casein solutions themselves. an in the Pper-color made from the casein, by means of the addition 75 underExample 1. The results obtained in Examples 6 to 9 inclusive plus thecontrol test are indicated in Table 111.

3'. of these relatively small amounts of trlbutyl with satisfac isolatedsoybean protein (which material is referred to in mixer ammonia in thiscase instead of "7 which has been pressed cold .or

smoothness is not needed, as in coating wall paper), instead of theisolated vegetable protein, we can use a solvent extracted seed meal,

e. g. a solvent extracted soybean 'press cake at 'a relatively lowtemperature. This material is ground to an extremely fine condition, andcan be used with or without milk' casein or isolated vegetable casein,being treated with tributyl citrate and thereafter dissolved in a mildlyalkaline solution,

with or without pigments and/0r dyes, and then used for coating paper.

It is to be understood that after applying the tributyl citrate to thecasein, the latter can be stored for a long time, or can be shipped,and/or compounded with any of the materials with which casein is usuallycompounded, before being dissolved, and the "non-foaming roperty of ,theso treated casein will persist. Thus we may treat the casein at thefactoryand ship this to a paper-coating mill to there be dissolved aswanted.

The term casein, as used in the appended,

claims, is intended to include milk casein and isolated vegetableproteins vegetable'casein". and the finely ground solvent-extracted seedmeal and also caseinates in general, such as sodium caseinate, ammoniumcaseinate,. magnesium caseinate, etc., which last three are compoundsof. milk casein with a small amount of soda, ammonia or magnesia.Mixtures of such materials are also included.

The casein is preferably, at the beginning of the step of oiling withthe citrate, in the usual air dry? conditiom-and the citrate can be usedalone or mixed with solvents or diluents v (e. g.

alcohol, etc), w ch also are non-aqueous liquids; but do not have to becompletely anhydrous.

The term non-aqueous liquids" is used in the appended claims todistinguish from liquids which consist largely of water.

The tributyl citrate, given in the above examples and specificdisclosure, is an alkyl citrate, and tributyl citrate is generally aboutthe most satisfactory alkyl citrate to employ. We do not desire torestrict all of the claims to the butyl compound, nor to the tri-alkylcompound, because alkyl citrate broadly, applied to the casein while thelatter is in the solid state will be (to some extent at least)eflective.

We claim:

l. A processof producing casein solutions of reduced, foaming tendencywhich comprises applying to solid casein, a small amount 01' tributyl cirate. the amount 01 the latter being not substantially above 5%, basedon the amount of said casein, and'thereafter dissolving the casein in anaqueous solvent.

2. A process which comprises agitating a mass of comm-muted solid caseinwhile spraying a substantially non-aqueous liquid material containingtributyl citrate upon said casein, the amount or said citrate'being notsubstantially more than 5 based on the casein, and thereafter dissolvingthe so-treated casein in any aqueous alkaline liq= uid, whereby a caseinsolution is produced having not more than a low foaming tendency.

3. Solid casein carrying" intimately incorporated therewith, an amountof tributyl citrate which is not substantially in excess of 5%, based onthe weight or the casein.

4. Solid casein wetted with a fraction of one per cent of tributylcitrate.

JOHN F. CORWIN. ROBERT c. wnrrn.

